The plow is being displaced by new techniques that protect the land and promise even more abundant crops

The 150-year era of the great steel plow, central instrument of American abundance and strength, is ending in an astonishing revolution now sweeping through Maryland and on to the Illinois bottomlands and the high hills of Oregon where corn, soybeans, wheat and cotton are grown. The upheaval in the long, quiet reaches of U.S. farmland has gone largely unnoticed in the din of presidential politics, the cries of rage from the torn inner cities, and the turmoil abroad. But it may mean as much to this country as all the other changes taking place around the world -- or even more.